Call it the best-kept business secret in Los Angeles.

After all, what other high-tech industry that spans the county, generates more than a billion dollars in revenue each year and employs tens of thousands of workers is so far under the radar?

But those indeed are the vital statistics of L.A.’s surprising medical device industry, much of which lies tucked away in non-descript office parks.

Medical devices, very basically, are pieces of equipment that hospitals, doctors and patients use. And innovative local companies as well as units of Fortune 500 giants are manufacturing everything from market-leading insulin pumps, to surgically implantable intraocular lenses, to tiny radioactive seeds designed to treat prostate cancer.

In fact, a recent report found that the region, including Orange County, has more medical device jobs than another part of the country. And it’s not happenstance. Many of the companies borrowed technologies from the region’s once robust aerospace sector, and then employed its highly skilled engineers as that sector declined.

This special report looks at the history, accomplishments and challenges facing the industry. It includes an article that explores how one community Chatsworth attracted a cluster of medical device companies. Fourteen prominent firms also are profiled.